Arachidic acid, also known as eicosanoic acid, is a saturated fatty acid with a 20-carbon chain. It is a minor constituent of cupuaçu butter (7%), perilla oil (0-1%), peanut oil (1.1%–1.7%), corn oil (3%), and cocoa butter (1%).
Its name derives from the Latin arachis — peanut. It can be formed by the hydrogenation of arachidonic acid.
Reduction of arachidic acid yields arachidyl alcohol.
Arachidic acid is used for the production of detergents, photographic materials and lubricants.